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PubMed1986

Differentiation of Cryptococcus neoformans serotypes by isoenzyme electrophoresis.

Cryptococcus neoformans has been divided into four serotypes by specific agglutination in immune rabbit sera. Based on mating characteristics of the perfect state and epidemiologic and biochemical differences, the serotypes have been divided into two major pairs. In an attempt to characterize the serotypes further, the authors studied 22 strains of C. neoformans by the technic of horizontal starch-gel isoenzyme electrophoresis. The glucose-phosphate isomerase and phosphoglucomutase of serotypes A, C, D, and a subset of the serotype B strains migrated to distinguishable locations in this system. The activities of the remainder of the serotype B strains co-migrated with the serotype C strains. Thus, this technic distinguishes all the serotypes of C. neoformans except for a subset of serotype B and should be a useful adjunct for further elucidation of the epidemiologic and biochemical differences among serotypes.

Cryptococcus↗
PubMedDate not supplied

Role of the capsule in phagocytosis of Cryptococcus neoformans.

The capsule is closely associated with the virulence of Cryptococcus neoformans. The capsule inhibits phagocytosis by macrophages, monocytes, and neutrophils. Studies in our laboratory have shown that incubation of encapsulated cryptococci in normal human serum leads to deposition of large amounts of C3 fragments at the surface of the yeast and lesser amounts of IgG within the capsule. Thus, the capsule mediates two biologic activities with opposing effects. It is our current view that phagocytosis of the yeast is dependent on a balance between the antiphagocytic action of cryptococcal polysaccharide and the ability of the yeast to focus opsonically active complement fragments and the IgG at the capsular surface.

Animals↗
PubMedDate not supplied

Capsular polysaccharides of Cryptococcus neoformans.

Polysaccharides of Cryptococcus neoformans are considered to have a role in the virulence of this encapsulated fungus. The structure has been determined for the most abundant polysaccharide, a glucuronoxylomannan of varying xylose and ester content. The structural complexity of the capsular material increases from serotype D to A to B to C, but even for the simplest capsule (type D), the immunodeterminants seem to occur only on the side chains. The interactions of some of these groups with antibodies is discussed.

Antibodies, Fungal↗
PubMed1975

Susceptibility of coccidioides immitis, Candida albicans, and Cryptococcus neoformans to amphotericin B, flucytosine, and clotrimazole.

Toxicity and failure of treatment with amphotericin B are stimuli for researchers to evaluate alternative antifungal antimicrobics. Also, data from susceptibility tests of Coccidioides immitis are sparse. With use of a defined, synthetic culture medium, C. immitis (25 strains). Candida albicans (21 strains), and Cryptococcus neoformans (21 strains) were tested against flucytosine, clotrimazole, and amphotericin B. Molecule for molecule, the sequency of activity was: clotrimazole greater than amphotericin B greater than flucytosine (totally inactive) C. immitis; and clotrimazole greater than amphotericin B greater than flucytosine with C. albicans and C. neoformans. With four strains of C. immitis, the minimal inhibitory concentration (of amphotericin B) was the same when inocula of arthrospores were tested as when corresponding spherules/endospores were tested simultaneously and identically. The clinical outcome of coccidioidomycosis in 17 patients treated with amphotericin B correlated best with minimal inhibitory concentration after incubation of cultures for 48 hr; a favorable response was associated with minimal inhibitory concentrations of less than or equal 1.0 mug/ml. Because clinical isolates of fungi appear to vary in susceptibility, in vitro tests may have clinical utility.

Adult↗
PubMed1976

Amphotericin B and amphotericin B methyl ester ascorbate. I. Chemotherapeutic activity against Candida albicans, Cryptococcus neoformans, and Blastomyces dermatitidis in mice.

Amphotericin B methyl ester (AME) has been reported to possess in vitro antifungal activity similar to that of amphotericin B and to have less intrinsic toxicity in mice and dogs. For these reasons AME has been porposed as an alternative to amphotericin B in the therapy of deep mycoses. For comparison of the therapeutic efficacy of the two polyenes in laboratory animals before initiation of studies in humans, groups of mice were infected with Candida albicans, Cryptococcus neoformans, and Blastomyces dermatitidis. Treatment consisted of two or more doses of each drug given by the intravenous route. Concurrently, studies of subacute toxicity were conducted in the same species to permit calculation of therapeutic indices. These studies have shown that AME, as the ascorbate salt, is substantially less efficacious than amphotericin B (in colloidal dispersion with sodium deoxycholate) for treatment of the fungal infections and that amphotericin B had a higher therapeutic ratio for all infections studied than did AME.

Amphotericin B↗
PubMed1977

Fungicidal components of mammalian granulocytes active against Cryptococcus neoformans.

Citric acid extracts of granule-rich fractions, prepared from rabbit and guinea pig heterophils or human neutrophis, killed Cryptococcus neoformans in vitro. These extracts sere fractionated by micropreparative electrophoresis on polyacrylamide gels. In preparation of rabbit and guinea pig heterophils, cryptococcidal activity was associated predominantely with lysosomal cationic protein complex. Human neutrophils lacked strictly comparable cationic proteins but contained other components that killed C. neoformans. These components appeared to be identical to previously described proteins of the human neutrophil active against Candida parapsilosis.

Animals↗
PubMed1982

Opsonic requirements for the uptake of Cryptococcus neoformans by human polymorphonuclear leukocytes and monocytes.

Chemiluminescence was used to determine opsonic requirements for interaction of Cryptococcus neoformans with human peripheral blood polymorphonuclear leukocytes (PMNLs) and monocytes (MNs). Peak chemiluminescence (mean +/- SD) was 172 +/- 25 X 10(3) for PMNLs and 50 +/- 13 X 10(3) for MNs with 20% pooled normal human serum vs. 10 +/- 3 X 10(3) for PMNLs and 6 +/- 1 X 10(3) for MNs without serum (P less than 0.005 for each comparison). The nature of the serum requirement was investigated; alternative pathway serum complements were necessary. The alternative pathway was activated directly by C. neoformans without the need for specific antibody. Chemiluminescence provided a quantitative and reproducible assay of the interaction of human phagocytes with C. neoformans and may be useful in studying opsonic requirements of other fungi.

Blood Physiological Phenomena↗
PubMed1988

Functional versus phenotypic analysis of T cells in subjects seropositive for the human immunodeficiency virus: a prospective study of in vitro responses to Cryptococcus neoformans.

We performed a prospective study of 50 subjects at high risk for human immunodeficiency virus (HIV) infection to determine if assays of antigen-specific T cell function provide an earlier indication of future progression to AIDS or a better assessment of immune function than do current methods of evaluation. We measured in vitro T cell responses to Cryptococcus neoformans and tetanus toxoid, response to mitogens, HIV p24 antigenemia, and clinical parameters. Progression to AIDS was significantly associated with loss of T cell response to cryptococci (P = .015), HIV antigenemia (P = .001), and low CD4+ cell numbers (P = .001). Most importantly, we found that loss of antigen-specific responses to cryptococci and tetanus can occur before changes in CD4 cell number. Abnormal response to mitogens and marked depletion of CD4+ cells were late signs of progressive HIV infection. Measurement of antigen-specific T cell function may be useful for assessing the efficacy of antiviral therapy in HIV infection before onset of symptoms.

Acquired Immunodeficiency Syndrome↗
PubMed1977

Epidemiologic differences among serotypes of Cryptococcus neoformans.

In the USA, the most prevalent serotype of the fungus, Cryptococcus neoformans, was serotype A. The serotype constituted 203 of 272 isolates from infections and 85 of 89 isolates from the environment. Serotype B or C isolates were infrequent causes of infection, except in Southern California, and were infrequent causes of infecand were not isolated at all from environmental sources. In Southern California, the absence of serotypes B and C in 67 soil and pigeon dropping isolates was striking, considering that 25 of 49 isolates from infections were serotypes B or C. The site in nature where serotypes B and C exist is currently unknown but differs from that of serotypes A and D. Serotype D may be unusually prevalent in both environmental and patient isolates from Denmark and Italy. Of 24 isolates from those countries, 21 were serotype D.

Animals↗
PubMed1984

Epidemiologic differences between the two varieties of Cryptococcus neoformans.

This report of the worldwide distribution of two varieties of Cryptococcus neoformans was drawn from data on 628 clinical isolates and from data on 97 additional isolates from other laboratories. Tests showed that 100% of the cultures from Austria, Belgium, Denmark, France, Germany, Holland, Italy, Switzerland, and Japan belonged to C. neoformans var. neoformans. More than 85% of the isolates from Argentina, Canada, the United Kingdom, and the United States (except southern California) were of C. neoformans var. neoformans, the remainder being of C. neoformans var. gattii . There was an unusually high prevalence (35-100%) of C. neoformans var. gattii in Australia, Brazil, Cambodia, Hawaii, southern California, Mexico, Paraguay, Thailand, Vietnam, Nepal, and countries in central Africa. These findings indicated that C. neoformans var. gattii is prevalent only in tropical and subtropical regions. Seventy per cent of the total isolates studied were of serotype A of C. neoformans var. neoformans. Serotype D (9% of the total) was common in Europe, but was found infrequently in other regions. Among the two serotypes of C. neoformans var. gattii , serotype B was 4.5 times more prevalent than serotype C. The majority (88%) of type C isolates in our collection were from southern California.

Africa↗
PubMed1975

Postitional specificity of fatty acids in pyrophosphatidic acid from Cryptococcus neoformans.

Pyrophosphatidic acid isolated from Cryptococcus neoformans was degraded to phosphatidic acid in aqueous pyridine. The phosphatidic acid was hydrolyzed by phospholipase A (EC 3.1.1.4) of Crotalus adamanteus to lysophosphatidic acid and 2-positioned fatty acids. From the analyses of the fatty acid composition of pyrophosphatidic acid and its degraded products (phosphatidid acid, lysophosphatidic acid, and fatty acid), it was concluded that most of the saturated fatty acids of pyrophosphatidic acid were at the 1,1'-positions while the unsaturated fatty acids were largely confined to the 2,2'-positions. The positional specificity of the fatty acids in pyrophosphatidic acid coincided with that of ordinary glycerophosphatides.

Chromatography↗
PubMed1989

Isolation of Cryptococcus neoformans from houses of AIDS-associated cryptococcosis patients in Bujumbura (Burundi).

Cryptococcus neoformans var. neoformans, which is responsible for AIDS-associated cryptococcosis in Bujumbura, was isolated in the domestic environment of seven out of 20 patients with AIDS-associated cryptococcosis. The findings prove that in his own domestic environment, the HIV-positive patient in central Africa is frequently exposed to the yeast and these observations lead us to insist on the suitability of carrying out a systematic survey by means of soluble antigens-sensitized latex in every HIV-positive patient. This also proves the importance of a follow-up of the 'cured' patients who easily can be recontaminated after their return home.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Melanogenesis in Cryptococcus neoformans.

Melanogenesis in Cryptococcus neoformans begins with the oxidation of dihydroxyphenylalanine by the enzyme phenol oxidase. The succeeding steps are very rapid. Two intermediates, dopachrome and 5,6-dihydroxyindole, have been isolated and characterized by high performance liquid chromatography. A pathway of melanin formation in C. neoformans is proposed, based on the presence of these intermediates.

Chemical Phenomena↗
PubMed1989

Electrophoretic karyotype of the pathogenic yeast Cryptococcus neoformans.

The electrokaryotype of the pathogenic yeast Cryptococcus neoformans is described for the first time. Three different patterns were seen: (a) serotypes B and C (variety gattii) are similar and consist of nine chromosome mobility groups of greater than 580 kb; (b) serotype A (variety neoformans) revealed eight chromosome-like groups greater than 700 kb; (c) serotype D (the second serotype of variety neoformans) not only differs from those described above, but each D isolate tested showed a different distribution of bands. The discrepancy, and the importance of electrokaryotyping as a taxonomic tool, are discussed.

Cryptococcus↗
PubMed1989

Restriction fragment polymorphism in mitochondrial DNA of Cryptococcus neoformans.

The restriction patterns of mitochondrial DNA from 20 isolates of the two varieties of Cryptococcus neoformans were compared. The patterns exhibited extensive heterogeneity among the isolates regardless of their serotype or varietal status. Hybridizations with cloned fragments of the conserved cytochrome oxidase gene from Saccharomyces cerevisiae exhibited at least seven patterns among the 20 isolates. There were, however, similarities in the restriction patterns among isolates within the same serotype that were not shared by isolates of other serotypes. Intra-varietal similarities were observed in the restriction patterns among the isolates of C. neoformans var. neoformans which were not present in the restriction patterns among the isolates of C. neoformans var. gattii. Hybridization of some cloned mitochondrial DNA fragments to total DNA digests of various isolates revealed polymorphic as well as variety-specific patterns of homology. These findings agree with the antigenic heterogeneity among the isolates and support the current taxonomic classification of C. neoformans into two varieties.

Blotting, Southern↗
PubMed2001

Hybrid genotypes in the pathogenic yeast Cryptococcus neoformans.

Amplified fragment length polymorphism (AFLP) genotyping of isolates of the pathogenic fungus Cryptococcus neoformans suggested a considerable genetic divergence between the varieties C. neoformans var. neoformans and C. neoformans var. grubii on the one hand versus C. neoformans var. gattii on the other. This divergence is supported by additional phenotypic, biochemical, clinical and molecular differences. Therefore, the authors propose the existence of two species, C. neoformans (Sanfelice) Vuillemin and C. bacillisporus Kwon-Chung, which differ in geographical distribution, serotypes and ecological origin. Within each species three AFLP genotypes occur, which differ in geographical distribution and serotypes. Differences in ecological origin (AIDS patients, non-AIDS patients, animals or the environment) were found to be statistically not significant. In C. neoformans as well as in C. bacillisporus one of the genotypes represented a hybrid. The occurrence of hybridization has consequences for the reproductive biology of the species, as new genotypes with altered virulence or susceptibility to antifungal drugs may arise through the exchange of genetic material.

AIDS-Related Opportunistic Infections↗
PubMed1978

Carriage of Cryptococcus neoformans in the crops of pigeons.

Cryptococcus neoformans was found in the crops of four (1.3%) of 319 pigeons in the Charity Bird Hospital and the University Campus, Delhi. It was demonstrated repeatedly at the Bird Hospital in old pigeon excreta as well as in the air. The findings substantiate the current view that the pigeon itself is not a reservoir of C. neoformans although it may serve as a carrier of the fungus.

Air Microbiology↗